The present invention relates to a heat exchanger for the implementation of a cooling of a liquid by a method of evaporation and adsorption. The principle of such a method of cooling consists of evaporating a liquid under the effect of a reduced pressure maintained by pumping of the vapors of said liquid.
The heat exchanger according to the invention is intended to be used in a receptacle in the form of a cooling dip tube or incorporated in a self-cooling drink container. The aim of the present invention is thus to allow the consumption of a drink at an ideal temperature at any place and at any time.
The implementation of the method of cooling by evaporation and adsorption is known and has been the subject of numerous research projects in the prior art. Numerous devices have been proposed, combining a heat exchanger containing a liquid to be evaporated with a reservoir containing an adsorbent, in particular for application in self-cooling drink containers.
Thus, U.S. Pat. No. 4,928,495, an illustration of which is given in FIG. 1, discloses a self-cooling container configuration 10 (presented as a can) comprising a heat exchanger 16 in flattened rectangular form, immersed in a drink to be cooled and connected to an adsorption device 22. This patent describes a basic scheme without specifying the means of realizing such a device taking account of the economic constraints associated with an application for disposable containers.
Moreover, International patent applications WO 01/10738 and WO 01/11297 of the same inventors, an illustration of which is given in FIG. 2, also disclose a self-cooling drink container 10 comprising a cylindrical U-shaped exchanger 30. These patent applications specify the geometry of the exchanger 30 as well as the method of manufacture and assembly of such a device, compatible with the industrial constraints of high-speed industrial manufacture of drink cans.
However, the exchanger 30 as it is disclosed has several drawbacks. In fact, the effectiveness of the heat exchange between the evaporator and the drink to be cooled, which governs the speed of cooling of the drink, depends chiefly on the geometry of the exchanger. In order to obtain a satisfactory cooling effectiveness, these patent applications propose increasing the dimension of the exchanger 30 to the maximum of what can possibly be inserted into the can, i.e. a diameter of 50 mm for a height of 100 mm. The volume of the resultant exchanger is 80 ml for a consumable drink volume of 300 ml, which represents more than 25%.
Another drawback of the device disclosed in the above-mentioned international applications relates to the quantity of metal necessary to produce this exchanger 30, therefore its cost. In particular, the water to be evaporated contained in the exchanger for the implementation of the method of cooling by adsorption evaporation must be kept under vacuum in the exchanger, and the difference in pressure between the inside and the outside of the exchanger 30 requires a significant thickness of metal constituting the walls of the exchanger.
Moreover, another drawback, linked to the particular geometry of the exchanger 30 disclosed in these international applications, lies in the requirement to use a gel to fix the cooling liquid in the exchanger in order to avoid the entrainment of the liquid by its own vapors during the operation of the device.
There is further known from FR 2,011,939 a self-refrigerating device for a drinks packaging that includes a conical-shaped heat exchanger containing a pressurised fluid such as liquified freon. Release of gas pressure to the outside atmosphere leads to cooling of the drink in contact with the heat exchanger. Adiabatic expansion of pressurized gas leads to a very significant drop in temperature allowing effective cooling of the drink despite a reduced surface of contact with the drink to be cooled. Nevertheless, this method of cooling is not compatible with industrial production techniques, the pressurized gas being somewhat difficult to handle. This method is also contrary to certain environmental protection standards aimed at reducing discharge of gas to the atmosphere.